A data center is a practical solution for cloud computing or large-scale application services or data services in information technology (IT) operations. One of the challenges of a data center is to provide uninterrupted power to computer server racks in the data center. For example, it is sometimes difficult to operate a power system continuously because of potential power surges and power outages (e.g., including loss of AC power, blackouts or brownouts). A data center can provide a backup power solution to its computer server racks. For example, the backup power solution can include a backup power generator that provides sustainable power after a power outage occurs. Because backup power generators are generally diesel engines based (e.g., a “Genset,” which is a combination of a diesel engine and an electric generator) and take time to start, the backup power generators oftentimes cannot supply power immediately after loss of main power, but normally after few tenths of seconds. Traditionally, after a power outage and before the genset backup power generator becomes fully operational, a backup battery system is used to provide backup power to the electrical load that would have been normally supported by the AC power grid. The battery power can be directly or indirectly supplied to computing devices or transformed to alternating current (AC), e.g., by using an inverter (e.g. UPS). However, batteries and battery systems have long term reliability problems unless they are frequently tested. Battery durability may be limited regardless, thus needing frequent replacements.
The figures depict various embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.